Method for removing impurities on MPCVD bulkhead

Abstract

The invention relates to a method for removing impurities on an MPCVD (Micro Pressure Chemical Vapor Deposition) bulkhead, aiming at solving the problem that the impurities on the bulkhead of MPCVD equipment are difficult to remove. The method for removing impurities on the MPCVD cabin wall comprises the following steps: 1, placing a sample support on a water cooling table to protect the water cooling table, closing a cabin cover of an MPCVD system, generating hydrogen-oxygen plasmas under the excitation of microwave energy, and etching the interior of the cabin body by using the hydrogen-oxygen plasmas; 2, wetting absorbent paper with deionized water to obtain wet absorbent paper, and then attaching the wet absorbent paper to the cabin wall of the MPCVD system; thirdly, the attached absorbent paper is taken down, the dust-free cloth is wetted with absolute ethyl alcohol, and the bulkhead is wiped clean; fourthly, the interior of a cabin of the MPCVD system is cleaned through a dust collector; and 5, generating the hydrogen-oxygen plasma again under the excitation of the microwave energy, and etching the interior of the treatment cabin again by using the hydrogen-oxygen plasma. The deposited impurities can be removed through oxyhydrogen plasma cleaning, deionized water infiltration and alcohol wiping.

Description

Technical Field

[0001] The invention belongs to the field of material preparation, and in particular relates to a method for removing impurities from an MPCVD bulkhead. Background Art

[0002] Diamond has emerged in the fields of integrated circuits, high-frequency communications, artificial intelligence, aerospace, etc. with its excellent optical properties, thermal conductivity and semiconductor properties. Even in some extreme application environments, diamond with ultra-high physical and chemical stability has become a key basic material. Diamond materials have been listed as emerging strategic materials, especially the artificial synthesis methods and synthesis equipment for large-size, high-quality single-crystal diamond materials, which are of great significance to the future development of the semiconductor industry. MPCVD process technology has become an ideal method for the preparation of large-size, high-quality single-crystal diamonds due to its clean energy source, no electrode pollution, high energy density and large effective deposition area. At present, the most promising method for the development of artificial diamonds is the MPCVD method. However, in the process of growing diamonds using MPCVD technology, a layer of impurities will be deposited on the bulkhead of the MPCVD system. The color of the impurities changes from light yellow to dark brown with the deposition time, and the thickness continues to increase. The impurities on the bulkhead will not only absorb impurity gases and affect the vacuum performance of the MPCVD system, but also the thin layer of impurities that fall off from the bulkhead during the growth process can easily fall onto the surface of the growth substrate, seriously affecting the normal growth process of diamond, leading to growth failure and causing huge economic losses. The current conventional pure plasma cleaning method cannot effectively clean the bulkhead and remove impurities. Therefore, a low-cost, fast and convenient impurity removal method is urgently needed for MPCVD equipment. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that impurities on the bulkhead of MPCVD equipment are difficult to remove, which affects the growth of CVD diamond, and to provide a method for removing impurities on the bulkhead of MPCVD equipment.

[0004] The method for removing impurities from the MPCVD bulkhead of the present invention is implemented according to the following steps:

[0005] 1. Bulkhead Hydrogen-oxygen plasma cleaning:

[0006] Place a sample holder on the water-cooling table to protect it, close the MPCVD system hatch, adjust the oxygen flow rate to 2-6sccm, the hydrogen flow rate to 198-194sccm, adjust the air pressure in the cabin to 13-15kpa, generate hydrogen-oxygen plasma under microwave energy excitation, use hydrogen-oxygen plasma to etch the inside of the cabin, and complete plasma cleaning;

[0007] 2. Infiltration: After the plasma etching is completed, open the hatch cover, wet the absorbent paper with deionized water to obtain wet absorbent paper, and then attach (wet compress) the wet absorbent paper to the (inner) bulkhead of the MPCVD system to make the bulkhead in a completely infiltrated state, and maintain the infiltrated state for 6-14 hours;

[0008] 3. Alcohol wiping: After the soaking is completed, remove the attached absorbent paper, wet the dust-free cloth with anhydrous ethanol, and wipe the cabin wall repeatedly;

[0009] 4. Impurity cleaning: Use a vacuum cleaner to clean the inside of the MPCVD system cabin and blow away the powdery and flake-like deposited impurities;

[0010] 5. Hydrogen-oxygen plasma re-cleaning:

[0011] Place a sample holder on the water-cooling table to protect it, close the MPCVD system hatch, adjust the oxygen flow rate to 2-6sccm, adjust the hydrogen flow rate to 198-194sccm, adjust the air pressure in the cabin to 13-15kpa, generate hydrogen-oxygen plasma under microwave energy excitation, and use hydrogen-oxygen plasma to etch the inside of the cabin again to complete the MPCVD cabin wall impurity removal method.

[0012] The present invention proposes a method for removing impurities from the MPCVD bulkhead by hydrogen-oxygen plasma cleaning, deionized water paper towel adsorption, and anhydrous ethanol wiping, optimizing the ratio of oxygen and hydrogen and the gas pressure, and increasing the process of wet compressing with wet absorbent paper. Although conventional plasma cleaning has a certain activation effect on impurities adsorbed on the bulkhead, it is impossible to directly remove the impurities by plasma etching, and the adsorption of the activated impurities to the bulkhead is still very strong, and it is impossible to remove them by wiping with a dust-free cloth or polishing with sandpaper. After plasma cleaning and activation of impurities, the present invention wet compresses the bulkhead with a deionized water paper towel to fully infiltrate the impurities. Under high humidity conditions, the adsorption of impurities to the bulkhead is significantly reduced, and a large area of ​​detachment occurs. Then, a dust-free cloth and anhydrous ethanol are used to wipe off the impurities that have not fallen off, and a vacuum cleaner is used to remove the residual powder. After the impurities in the bulkhead are removed, the bulkhead is plasma cleaned again to remove impurities such as dust and inorganic compounds introduced in the cleaning step, and the bulkhead cleaning is completed.

[0013] The present invention provides a method for removing impurities from an MPCVD chamber wall, wherein the impurities are removed through hydrogen-oxygen plasma cleaning, deionized water infiltration, alcohol wiping, impurity cleaning, and hydrogen-oxygen plasma cleaning.

[0014] The MPCVD bulkhead impurity removal method of the present invention has the following beneficial effects:

[0015] 1. The process of removing impurities from the MPCVD bulkhead of the present invention is simple. Through hydrogen-oxygen plasma cleaning and deionized water infiltration, alcohol wiping can remove the deposited impurities with strong adsorption and extremely difficult to remove.

[0016] 2. The impurity removal effect is good and it can remove almost all the deposited impurities in the wetted areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a photo of the MPCVD bulkhead before impurities are removed in the embodiment;

[0018] Figure 2 This is a photo of wet absorbent paper attached to the bulkhead of the MPCVD system in step 2 of the embodiment;

[0019] Figure 3 This is a photo of the MPCVD cabin wall after impurities are removed in the embodiment. DETAILED DESCRIPTION

[0020] Specific implementation method 1: The method for removing impurities from the MPCVD bulkhead in this implementation method is implemented according to the following steps:

[0021] 1. Bulkhead Hydrogen-oxygen plasma cleaning:

[0022] Place a sample holder on the water-cooling table to protect it, close the MPCVD system hatch, adjust the oxygen flow rate to 2-6sccm, the hydrogen flow rate to 198-194sccm, adjust the air pressure in the cabin to 13-15kpa, generate hydrogen-oxygen plasma under microwave energy excitation, use hydrogen-oxygen plasma to etch the inside of the cabin, and complete plasma cleaning;

[0023] 2. Infiltration: After the plasma etching is completed, open the hatch cover, wet the absorbent paper with deionized water to obtain wet absorbent paper, and then attach (wet compress) the wet absorbent paper to the (inner) bulkhead of the MPCVD system to make the bulkhead in a completely infiltrated state, and maintain the infiltrated state for 6-14 hours;

[0024] 3. Alcohol wiping: After the soaking is completed, remove the attached absorbent paper, wet the dust-free cloth with anhydrous ethanol, and wipe the cabin wall repeatedly;

[0025] 4. Impurity cleaning: Use a vacuum cleaner to clean the inside of the MPCVD system cabin and blow away the powdery and flake-like deposited impurities;

[0026] 5. Hydrogen-oxygen plasma re-cleaning:

[0027] Place a sample holder on the water-cooling table to protect it, close the MPCVD system hatch, adjust the oxygen flow rate to 2-6sccm, adjust the hydrogen flow rate to 198-194sccm, adjust the air pressure in the cabin to 13-15kpa, generate hydrogen-oxygen plasma under microwave energy excitation, and use hydrogen-oxygen plasma to etch the inside of the cabin again to complete the MPCVD cabin wall impurity removal method.

[0028] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that the microwave power is controlled to be 3-3.6 kw in step 1.

[0029] Specific implementation method three: The difference between this implementation method and specific implementation method one or two is that in step one, the oxygen flow rate is adjusted to 2 sccm, the hydrogen flow rate is adjusted to 198 sccm, the air pressure in the cabin is adjusted to 15 kpa, the microwave power is 3.6 kW, and hydrogen-oxygen plasma is generated under microwave energy excitation.

[0030] Specific implementation method 4: This implementation method is different from any one of specific implementation methods 1 to 3 in that the time for etching the chamber body using hydrogen-oxygen plasma in step 1 is 8-12 hours.

[0031] Specific implementation method five: This implementation method is different from any one of specific implementation methods one to four in that in step two, during the process of attaching the wetted absorbent paper to the (inner) bulkhead of the MPCVD system, the absorbent paper is re-wetted with deionized water every 3-4 hours.

[0032] Specific implementation method 6: This implementation method is different from specific implementation methods 1 to 5 in that the infiltration state is maintained for 8-12 hours in step 2.

[0033] Specific implementation method seven: The difference between this implementation method and any one of specific implementation methods one to six is ​​that in step five, the oxygen flow rate is adjusted to 2 sccm, the hydrogen flow rate is adjusted to 198 sccm, the air pressure in the cabin is adjusted to 15 kpa, the microwave power is 3.6 kW, and hydrogen-oxygen plasma is generated under microwave energy excitation.

[0034] Specific implementation eight: This implementation differs from specific implementation seven in that in step five, the chamber body is etched again using hydrogen-oxygen plasma for 8-12 hours.

[0035] Specific implementation method 9: This implementation method is different from specific implementation methods 1 to 8 in that the sample holder described in step 1 and step 5 is a molybdenum sample holder.

[0036] Embodiment: The method for removing impurities from the MPCVD bulkhead of this embodiment is implemented according to the following steps:

[0037] 1. Bulkhead Hydrogen-oxygen plasma cleaning:

[0038] A molybdenum sample holder was placed on the water-cooling table to protect it, the MPCVD system hatch was closed, the oxygen flow rate was adjusted to 2 sccm, the hydrogen flow rate was adjusted to 198 sccm, the air pressure in the cabin was adjusted to 15 kPa, the microwave power was 3.6 kW, hydrogen-oxygen plasma was generated under microwave energy excitation, the interior of the cabin was etched with hydrogen-oxygen plasma for 12 hours, and plasma cleaning was completed;

[0039] 2. Wetting: After the plasma etching is completed, open the hatch cover, wet the medical absorbent paper with deionized water to obtain wet absorbent paper, and then attach the wet absorbent paper to the (inner) bulkhead of the MPCVD system to make the bulkhead in a completely wet state. Keep the wet state for 12 hours, and re-wet the medical absorbent paper with deionized water every 4 hours to maintain a humid environment inside the cabin;

[0040] 3. Alcohol wiping: After the soaking is completed, remove the attached absorbent paper, wet the dust-free cloth with anhydrous ethanol, and wipe the bulkhead repeatedly until all the deposited impurities adsorbed on the bulkhead are wiped off;

[0041] 4. Impurity cleaning: Use a vacuum cleaner to clean the inside of the MPCVD system cabin and blow away the powdery and small-piece deposited impurities;

[0042] 5. Hydrogen-oxygen plasma re-cleaning:

[0043] A molybdenum sample holder is placed on the water-cooling table to protect it, the MPCVD system hatch is closed, the oxygen flow rate is adjusted to 2 sccm, the hydrogen flow rate is adjusted to 198 sccm, the air pressure in the cabin is adjusted to 15 kPa, the microwave power is 3.6 kW, hydrogen and oxygen plasma is generated under the excitation of microwave energy, and the interior of the cabin is etched again with hydrogen and oxygen plasma for 12 hours to complete the MPCVD cabin wall impurity removal method.

[0044] The removal effect of impurities on the MPCVD bulkhead in this embodiment is shown in Figure 1-Figure 3 As shown, if only the hydrogen-oxygen plasma cleaning of step 1 is performed, the adsorption of impurities to the bulkhead is still very strong, and the impurities on the MPCVD bulkhead cannot be removed. The method for removing impurities from the MPCVD bulkhead of this embodiment can completely remove the dark brown impurities adsorbed on the bulkhead, so that the bulkhead of the MPCVD system can be restored to cleanliness, and even to the factory state.

Claims

1. A method for removing impurities from an MPCVD bulkhead, characterized in that The MPCVD bulkhead impurity removal method is implemented according to the following steps:

1. Bulkhead Hydrogen-oxygen plasma cleaning: Place a sample holder on the water-cooling table to protect it, close the MPCVD system hatch, adjust the oxygen flow rate to 2-6sccm, the hydrogen flow rate to 198-194sccm, adjust the air pressure in the cabin to 13-15kpa, generate hydrogen-oxygen plasma under microwave energy excitation, use hydrogen-oxygen plasma to etch the inside of the cabin, and complete plasma cleaning; 2. Infiltration: After the plasma etching is completed, open the hatch cover, wet the absorbent paper with deionized water to obtain wet absorbent paper, and then attach the wet absorbent paper to the bulkhead of the MPCVD system to make the bulkhead in a completely infiltrated state, and maintain the infiltrated state for 6-14 hours; 3. Alcohol wiping: After the soaking is completed, remove the attached absorbent paper, wet the dust-free cloth with anhydrous ethanol, and wipe the cabin wall repeatedly; 4. Impurity cleaning: Use a vacuum cleaner to clean the inside of the MPCVD system cabin and blow away the powdery deposited impurities; 5. Hydrogen-oxygen plasma re-cleaning: Place a sample holder on the water-cooling table to protect it, close the MPCVD system hatch, adjust the oxygen flow rate to 2-6sccm, adjust the hydrogen flow rate to 198-194sccm, adjust the air pressure in the cabin to 13-15kpa, generate hydrogen-oxygen plasma under microwave energy excitation, and use hydrogen-oxygen plasma to etch the inside of the cabin again to complete the MPCVD cabin wall impurity removal method.

2. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that In step 1, the microwave power is controlled to be 3-3.6 kW.

3. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that In step 1, the oxygen flow rate is adjusted to 2 sccm, the hydrogen flow rate is adjusted to 198 sccm, the air pressure in the cabin is adjusted to 15 kPa, and the microwave power is 3.6 kW to generate hydrogen-oxygen plasma under microwave energy excitation.

4. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that In step 1, the chamber body is etched by hydrogen-oxygen plasma for 8-12 hours.

5. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that In the process of attaching the wetted absorbent paper to the bulkhead of the MPCVD system in step 2, the absorbent paper is re-wetted with deionized water every 3-4 hours.

6. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that In step 2, the infiltration state is maintained for 8-12 hours.

7. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that In step five, the oxygen flow rate is adjusted to 2 sccm, the hydrogen flow rate is adjusted to 198 sccm, the air pressure in the cabin is adjusted to 15 kPa, and the microwave power is 3.6 kW to generate hydrogen-oxygen plasma under microwave energy excitation.

8. The method for removing impurities from the MPCVD bulkhead according to claim 7, characterized in that In step 5, the chamber body is etched again using hydrogen-oxygen plasma for 8-12 hours.

9. The method for removing impurities from the MPCVD bulkhead according to claim 1, characterized in that The sample holder described in step 1 and step 5 is a molybdenum sample holder.

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